Tracking a bug is much easier and communicative when done through a tool.
format of the tool:
BUG ID TEST CASE ID DESCRIPTION SEVEORITY PRIORITY ASSIGNED TO STATUS REMARKS
(bug id is usually generated by the tool)
outside the excel sheet we might need to fill the fields like:
tester name (uasually genrated with the login name)
date of execution etc.
a and < cancel> button
Bug tracking in excel sheet is not feasible, once u start using tracking tool u can understand.
on severity,
1] Show stopper - an bug which makes you cannot test the product further
2] Severe - some Functionality is not working
3] Major - Functionality breaks during normal operation sometimes
4] Minor - it a least one like GUI errors/spell mistakes/color differences.